* {
    margin: o;
    padding: 0;
    box-sizing: border-box;
}
a {
    list-style: none;
}
li {
    list-style: none;
}
.lunbo {
    width: 100%;
}
.content {
    width: 800px;
    height: 500px;
    margin: 20px auto;
    position: relative;
}
#item {
    width: 100%;
    height: 100%;
    z-index: 5;
}
.item {
    position: absolute;
    opacity: 0;
    transition: all 1s;
    /* 过渡的时候的渐变效果 */
    z-index: 5;
}
.item.active {
    opacity: 1;
}
img {
    width: 100%;
}
#left {
    width: 30px;
    height: 70px;
    font-size: 30px;
    color: white;
    background-color: rgba(0, 0, 0, 0.4);
    line-height: 70px;
    padding-left: 5px;
    z-index: 100;
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-60%);
    cursor: pointer;
    opacity: 0;
    border-radius: 2px;
}
.lunbpo:hover #left {
    opacity: 1;
}
#right{
    width: 30px;
    height: 70px;
    font-size: 30px;
    color: white;
    background-color: rgba(0, 0, 0, 0.4);
    line-height: 70px;
    padding-left: 5px;
    z-index: 10;
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-60%);
    cursor: pointer;
    opacity: 0;
    border-radius: 2px;
}
.lunbpo:hover #right {
    opacity: 1;
}
#circle{
    height: 20px;
    display: flex;
    position: absolute;
    bottom: 36px;
    right: 25px;
     z-index: 10;
}
.circle{
    width:10px;
    height: 10px;
    border-radius: 5px;
    border: solid 2px white;
    background:rgba(0, 0, 0, 0.4);
    cursor: pointer;
    margin: 5px;
   
}
.white{
    background-color: #fff;
}